7.1

CVE-2020-24240: gnu bison Use After Free

CVSS: 7.1v2.0HighModified
AliasesALPINE-CVE-2020-24240UBUNTU-CVE-2020-24240DEBIAN-CVE-2020-24240
Published 25-08-2020Last modified 04-08-2024
Open JSON

Vulnerability summary

CVE-2020-24240 is a high (CVSS 7.1) Use After Free vulnerability in gnu bison. EPSS estimates a 1.26% chance of exploitation in the next 30 days, higher than 69.3% of scored vulnerabilities.

Overall risk
29/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.1/10
010
High · v2.0 (NVD)
EPSS score
1.26%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 0 · Duplicates 1
CVE-2020-16132

Timeline

  1. 25-08-2020
    PublishedVulnerability first disclosed.
  2. 04-08-2024
    Last modifiedVulnerability information updated.

Description

GNU Bison before 3.7.1 has a use-after-free in _obstack_free in lib/obstack.c (called from gram_lex) when a '\0' byte is encountered. NOTE: there is a risk only if Bison is used with untrusted input, and the observed bug happens to cause unsafe behavior with a specific compiler/architecture. The bug report was intended to show that a crash may occur in Bison itself, not that a crash may occur in code that is generated by Bison.

CVSS metrics

5 scores · 4 sources · 2 versions

EPSS trend

Probability

1.26%

Chance of exploitation in the next 30 days

Percentile

69%

Versus all other CVEs

30-day change

0.00 pp

From 1.26% on 20-09-2026

20-09-202620-10-2026
EPSS score
1.26%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Alpine1 product
  • bison< 3.7.2-r0
Debian1 product
  • bison< 2:3.7.2+dfsg-1
Gnu1 product
Ubuntu1 product
  • bisonAll versions (No fix recorded)

4 vendors · 4 products

References

7 links